This invention relates to a support device for semi-trailer with a support leg, on the lower end of which a base receiving device is located, and with a support base with a base plate, which is mounted by means of two vertical plates on the base receiving device so that it can move in the vertical direction and can pivot, and with at least one damping element located between the base plate and the base receiving device.
Support devices are generally located in pairs on the underside of semi-trailers in their forward areas, and are always used when the semi-trailer is separated from its tractor and is parked by itself. In systems of the prior art, on semi-trailers with air springs, air will almost inevitably have escaped from the springs after the semi-trailer has been parked for a more or less long period of time, as a result of which the rear portion of the semi-trailer droops and the semi-trailer assumes a diagonal position or a position in which it tilts toward the rear in relation to the ground. For this purpose, the support bases or their base plates must be able to swivel, to compensate for this inclined position. The same requirement applies if the semi-trailer is parked on ground that is uneven or not level. In addition to the pivoting capability of the base or of the base plate, it is desirable that, as the support devices are being extended, the movable parts of the support device come to rest gently on the ground so that they are not damaged. For this purpose, corresponding damping elements are located in the support bases.
Because it is very difficult to satisfy all these peripheral requirements with only one model of the base, the general practice is to install different model bases as a function of the conditions in which they will be used.
The required model must generally be defined prior to the purchase of the support winch, because the support base is a component of the winch, and must accordingly be mounted on it.
The different realization of the base generally also requires different arrangements and preparatory steps on the support winch itself. Consequently, there is a specific model of support winch for each type of base. This has the advantage that the base and the support winch can be optimally coordinated with each other, although that, too, has several disadvantages.
For example, during the process of manufacturing the support winch, a great many different manufacturing operations have to be performed for each model, which entails a correspondingly high cost for tools, jigs, inventories of material, space and logistics. Moreover, once the support winch has been manufactured, it is generally no longer possible for the final consumer or the retail dealer to exchange different base models for one another.
It is therefore desirable to develop different model bases that can be used in as many applications as possible, and accordingly have a wide range of potential applications.
The prior art includes one model of a foot which is essentially a rigid structure which has a plate-shaped ground contact surface and can pivot around an axle which is mounted horizontally in the inner tube of the support winch, transverse to the direction of travel. The support foot can adapt to certain inclinations of the road, e.g. entrance ramps, hills and similar inclinations, and can thus be used to park the semi-trailer.
As a result of the inherently rigid realization of the support base, however, impact loads of the type that occur, for example, during the shunting of the semi-trailer, are transmitted directly to the support winch and indirectly to the vehicle. Ultimately, these impacts can lead to disruptions in operation or even damage to both the winch and the vehicle.
To reduce such damage or to eliminate it altogether, there are models of bases that have elastic elements that absorb the kinematic energy of the impact and can thus protect the mechanical components.
DE 31 19 359 A1 discloses a support device in which, on the lower end of the support part to be deployed, there is a ground plate that projects laterally beyond this support part, whereby between this ground plate and the base plate there is an elastic pressure body which is designated the damping element and is made of rubber. A retaining ring that is welded to the base plate has an upper peripheral segment that overlaps and grips the laterally projecting ring-shaped portion of the ground plate, whereby there is a certain amount of play between the retaining ring and the extendable support part. The pivot angle and the deflection travel of the base plate are limited by the compressibility of the elastic pressure body and the distance between the retaining ring and the extendable support part. In this support device there is no pivot bearing. This design gives the base plate only a limited ability to adapt to major uneven spots in the ground, whereby the damping element is deformed both when the base is set down in the vertical direction, as well as when the base is tipped.
EP 0 430 643 A2 discloses a support base, in which the fastening to the base receiving device is identical with the pivot bearing of the base. A tubular bearing element is located in a rectangular housing of the base retaining device and is held so that it can move vertically in slots in two vertical plates that are fastened to the base plate. Between the housing and the base plate there is a damping element which is compressed when the base is set down. An additional deformation in the transverse direction occurs when the base pivots, as a result of which the housing must be pushed over the damping element. This arrangement has a number of disadvantages.
The damping element Is exposed to significant and different loads, which leads to rapid material fatigue. The pivoting process is prevented and limited by the damping element. When the support base Is retracted, it remains in its pivoted position, because the damping element prevents it from pivoting back into its initial position. When the support base is lowered again, the damping element can interfere with the free movement of the base and damage it.
U.S. Pat. No. 3,666,290 describes a support base in which there are two damping elements between a plate attached to the end surface of the support tube and the base plate. Above the damping element, there is a pivot bearing which consists of a bolt inserted through the support tube, which Is oriented so that it can move in two slots of two vertical plates fastened to the base plate. In this arrangement of the support base, too, the damping elements are additionally deformed during pivoting, as a result of which the pivot angle is limited.
Starting from the prior art as described in U.S. Pat. No. 3,666,290, the object of the invention is to create a support device with a support base which has an improved pivoting capability, whereby an additional object is to subject the damping element to reduced deformation.
The invention teaches that this object is achieved with a support device in which the damping element is located so that it cannot pivot on the underside of the base receiving device and is supported on a curved plate which is fastened to the base plate, whereby the contour of the curved plate is adapted to the pivoting movement of the base plate with reference to the support leg.
As a result of stationary location of the damping element on the underside of the base receiving device, the damping element does not accompany the pivoting movement of the base when the latter pivots. The damping element is therefore compressed only in the vertical direction in every pivot position. The curved plate guarantees that the damping element can be optimally supported in any pivot position.
The damping element can be fastened to the underside of the base receiving device or, in one preferred embodiment, can be fastened to the pivot bearing device by means of a holding device.
The holding device, which can consist of two oblong retaining plates, is located in the pivot bearing device so that it can move vertically, so that when a load is applied it can move upward until it comes in contact with a stop, whereby the damping element is compressed. The stop can be formed by slots, for example, in which the bolts of the pivot bearing device move in the vertical direction.
So that the damping element remains stationary below the base receiving device, in particular in the embodiment that has two retaining plates, at least one stabilizer toe is located on the base receiving device which is engaged on the damping element.
The damping element preferably consists of a roller made of elastic material. A roller offers the advantage that the contact surface on the relatively small compared with plate-shaped damping elements, so that if the roller is mounted so that it cannot rotate, only small friction forces occur during pivoting, which means that when the base is raised, it can pivot back into its starting position.
This process is facilitated if, as in an additional embodiment, the roller is rotationally fastened in the holding device. As a result, the material of the roller is protected even during pivoting, because the roller can roll along the surface of the curved plate during a pivoting movement.
The longitudinal axis of the roller is preferably oriented parallel to the pivoting axis of the support base.
The curved plate preferably has a concave surface on the side facing the damping element.
The support device offers the advantage that the wear on the damping element is low. The pivot angle of the support base is far larger than on support bases of the prior art that have a damping element, because the damping element does not restrict or interfere with the pivot process. As a result of the pivoting fastening of the support base in the pivot bearing device on the support base, a stable arrangement is created, so that even transverse forces can be absorbed safely.